The Structure and composition of musculoskeletal tissues are tailored to meet their demanding functions. With injury, the structure and composition of these tissues deteriorate, resulting in a decline or loss of mechanical function. Musculoskeletal tissues each have a wide array of compositional and structural variety with respect to collagen and proteoglycan types, as well as other extracellular matrix constituents and factors. Careful description and quantification of tissue structural organization and composition, as well as localization and identification of growth factors and cytokines, are necessary requirements for elucidation of the biologic mechanisms underlying musculoskeletal integrity, injury, and repair. The overall objective of this Histology Core (HC) is to develop and utilize a wide range of histological and histomorphometric approaches to evaluate musculoskeletal tissue injury and repair, and to provide training and funding for new projects and collaborations utilizing these assays. The Specific Aims are: Aim 1: To provide guidance and training on the capabilities, advantages, and disadvantages of the various methodologies to assess musculoskeletal tissue structure and composition through formal educational enrichment programs and one-on-one interactions. Aim 2: To provide expertise and service for histological and histomorphometric assays of musculoskeletal tissues. Aim 3: To develop new histologically-based techniques that will be applicable to musculoskeletal research. Aim 4: To provide funding for development of new projects and collaborations and to develop preliminary and/or feasibility data for investigators.